Anodic oxidation- and hydrogenation-produced TiO₂ nanotubes on titanium and its effect on gingival epithelial cell adhesion ability

Abstract

The gingival epithelium plays a crucial role in achieving long-term stability of dental implants, and the hydrogenated TiO2 nanotubes with a superhydrophilic surface exhibit more excellent biological activity than pure titanium implants. However, the effects of the hydrogenated TiO2 nanotubes on human gingival epithelial cells remain unclear. Here, we fabricated hydrogenated TiO2 nanotubes using anodization and hydrogenation to investigate the adhesion of human gingival epithelial cells (HGEs) on structured surfaces in vitro. The topography, roughness, and wettability of three sample types—titanium (Ti), TiO2 nanotubes (TNTs), and hydrogenated TiO2 nanotubes (H2-TNTs)—were characterized. To evaluate cell adhesion, the HGEs were co-cultured with these specimens. This allowed for the examination of both the adhesion morphology and the number of cells adhering to each material's surface. Expression levels of genes and proteins related to cell adhesion were also assessed. H2-TNTs demonstrated nanoscale topography similar to TNTs in terms of diameter and height and maintained a superhydrophilic surface (with a static water contact angle of < 5°). The number of HGEs adhering to H2-TNTs was notably higher. Furthermore, HGEs on H2-TNTs displayed a more stretched morphology in comparison to the other two groups. Notably, the expression levels of adhesion-related genes and proteins in H2-TNTs surpassed those of the other two groups. Hence superhydrophilic H2-TNTs significantly enhance the adhesion ability of HGEs on the material surface.